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Kris\Slyka's posts Post Back to profile
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Leeloo

@slyka @miunau
Try with a pressed CD. The data is a thin aliminium layer right under the label, so cutting the shiny side should not get anywhere near the aluminium layer.

CD players were always promised to be able to ignore scratches, I wonder if they are able to read through this intentional scratch.

26 August at 14:58 | Wall-to-wall | Open on techhub.social
7 comments
Kris\Slyka

@leeloo but… that's exactly what I did in the video? Wether or not the it's a CD-R or a normal CD makes no difference in the layer stackup :blobfoxconfused:

26 August at 16:28 | Open on pawb.fun
Leeloo

@slyka
I was not aware of the layering of CDRs.

So, did it play in a CD player? Was it able to ignore the "scratch"?

26 August at 16:41 | Open on techhub.social
Kris\Slyka

@leeloo I don't have anything to read CDs with anymore, but I doubt it. Even though there is some amount of error correction in CDs this basically completely covers a continuous section of the surface in relatively deep scratches

26 August at 16:43 | Open on pawb.fun
Leeloo

@slyka
But the claim is that the laser is not focusing on the scratch, so it should be able to look right past it.

26 August at 16:45 | Open on techhub.social
Kris\Slyka

@leeloo it's still an interface between two materials with different refractive indexes, which due to the grooves ends up at pretty steep angles. That's gonna refract the light all over the place wether it's focused on the interface or not. I'd love to be proven wrong but I don't really see that working too well

26 August at 16:52 | Open on pawb.fun
Leeloo

@slyka
I know, that's why I would like to see the results.

I'll be impressed if it can play, but might also say something about false advertising if it doesn't.

26 August at 17:09 | Open on techhub.social
Alan Miller :verified_paw:

@leeloo @slyka a CD player would work for discs with low amounts of data because the central part of the disc isn't affected. The cut part would almost certainly be unreadable because of what's basically a diffraction grating cut into it.

26 August at 19:28 | Open on infosec.exchange
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